[Bug middle-end/101530] ICE: 'verify_gimple' failed: non-top-level 'bit_field_ref' with __builtin_shufflevector()[0]

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101530

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-07-21

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I don't think we need V_C_E <BIT_FIELD_REF <>> on the LHS, V_C_E is not
size-changing so you can do

 BIT_FIELD_REF <> = V_C_E <>

instead, thus move the V_C_E to the RHS.  We're restricting BIT_FIELD_REFs
to produce is_gimple_reg_type so for the case in question we're expecting

 D.1234 = BIT_FIELD_REF <_1, 32, 0>;
 _2 = VIEW_CONVERT_EXPR<int> (D.1234);

of course we could have folded the BIT_FIELD_REF which produces a V1SI to
produce a SI, consuming the VIEW_CONVERT_EXPR.

I guess we need similar handling for compound_lval components as we have
for toplevel VIEW_CONVERT_EXPR:

        case VIEW_CONVERT_EXPR:
          if ((fallback & fb_rvalue)
              && is_gimple_reg_type (TREE_TYPE (*expr_p))
              && is_gimple_reg_type (TREE_TYPE (TREE_OPERAND (*expr_p, 0))))
            {
              ret = gimplify_expr (&TREE_OPERAND (*expr_p, 0), pre_p,
                                   post_p, is_gimple_val, fb_rvalue);
              recalculate_side_effects (*expr_p);
              break;
            }